The purpose of this study is to provide a direct determination of the cariogenic potential of dental plaque from different minority groups through the chemical analysis of whole plaque and its extracellular aqueous phase, referred to as plaque fluid. The cariogenic potential of plaque is primarily influenced by the degree of saturation with respect to tooth mineral and levels of organic acids in plaque fluid, obtained following sucrose exposure. In addition, the mineral ion content of whole plaque appears also to be a caries determinant. These important factors will be assessed in selected groups of Caucasian, Hispanic, Asian, Pacific islanders, and Black subjects who are either caries-free or caries- positive and correlated with other clinical parameters and. in conjunction with the Microbiological Core, with the microbial composition of plaque. These studies will provide a rational basis for differences in caries susceptibility observed in certain minority populations. Total concentrations of inorganic and organic acid ions will be determined in plaque fluid obtained from coronal surfaces of individual members of the various ethnic and racial populations, before and after sucrose exposure. These data will be used to calculate the degree of saturation with respect to tooth mineral. The calcium, phosphate and fluoride contents of whole plaque will also be determined. The combined data will be correlated with the microbiological composition of plaque from the same subject, as described within the Microbiological Core. In addition, findings will also be correlated with other clinical parameters (e.g. fluoride history, dietary habits, salivary flow, plaque index) and the assessment (Spielman/Hay) of adhesion-promoting salivary proteins in the different population samples.